(a) Technical Field
The present disclosure relates generally to smart glass using a guided self-assembled photonic crystal, and more particularly to such a photonic crystal having a photonic crystal layer interposed between a pair of conductive glass plates.
(b) Background Art
“Smart glass” refers to an active control technology capable of reducing energy loss by freely adjusting the transmittance of light inflowing from outside and providing a pleasant environment for consumers. This is considered to be a basic technology capable of being commonly used in various industrial fields such as transportation, information display and architecture. Smart glass is expected to be actively used in various fields since smart glass may induce instant state changes by simple operation and provide various conveniences.
Smart glass has been manufactured using a polymer dispersed liquid crystal (hereinafter, “PDLC”) technology. A PDLC has a structure in which micron-size liquid crystal particles are dispersed into a polymer matrix, and light transmittance is adjusted by a refractive index difference between the liquid crystal particles and the polymer caused by an external voltage. In an Off state, in which voltage is not applied, liquid crystal particles (91) are irregularly arranged, and light scatters due to the refractive index difference between the liquid crystal particles (91) and a polymer matrix (93) as shown in FIG. 1 (a). In an On state, in which voltage is applied, light penetrates since liquid crystal particles (91) are oriented to have the same refractive index as the polymer matrix (93), as shown in FIG. 1 (b).
A PDLC uses a polymer matrix, therefore, there are problems in that a haze phenomenon may occur in smart glass, in which a turbid color is obtained, and when exposed to ultraviolet light, a yellowing phenomenon may occur due to the curing or alteration of the polymer.
In addition, in a PDLC, liquid crystal particles are irregularly arranged in an Off state, and incident light irregularly scatters. Thus, a specific color is difficult to be obtained since lights in various wavelength ranges are all mixed. When a dye is added in order to color the PDLC, the transmittance of light decreases since the dye absorbs light due to its nature, which causes a problem of degrading efficiency of the PDLC itself.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.